Hot dip galvanizing apparatus



June 19, 1956 M. P. DANIEL 2,750,923

HOT DIP GALVANIZING APPARATUS med Nov. 2e. 1952 NIW 1|' www III l||| 2,750,923 HOT DIP GALvA'NIzlNG APPARATUS Marvin P. Daniel, Chicago, Ill., assignor to General Electric Company, a corporation of New `iork Application November 28, 1952, Serial No. 323,038

4 Claims. (Cl. 118--423) This invention relates to an improved conveyor system for transporting articles with respect to a liquid-treatment bath and, in particular, to a conveyor system by means of which the work may be caused abruptly to travel at various levels during passage through the bath or upon removal therefrom.

Although my invention is not limited to any particular liquid-'treatment application, it is advantageously employed in electroplating or hot-dip galvanizing, in each of which processes it is desirable to bump or jar the work while itis in a bath or after it has emerged therefrom. In galvanizing, for example, jarring or agitating the Work while it is submerged in the zinc Will assist in cleaning the surface of the work. A good bond is then quickly established between the zinc and the body of the article being coated. When the work emerges from the bath, it is accepted practice to remove surplus zinc by bumping or jarring the article to release the droplets which accumulate about the bottom thereof, thus re- --covering zinc and improving the appearance of the coating. In electroplating, agitation of the work while it is in the plating solution will remove from the work any gas bubbles which may have accumulated thereon and raising or lowering the work for predetermined travel at various levels within the bathbrings the work into .'Zones of possibly greater ion concentration.

It is Aan object of this invention to provide means whereby a conventional monorail conveyor may be adapted as needed to provide for sharply jarring the work as it passes through the bath or after it has been removed therefrom.

It is another object of the invention to provide means adaptable for installation along a conveyor rail to cause the work to raise above the normal level of travel and then suddenly drop in one or more steps to travel at a different 'level or levelsthrough a treatment bath.

It is a furtherobject of the invention to provide an improved galvanizing method.

In a presently preferred embodiment of the invention, I apply to a conveyor rail of conventional inverted T- section, a short lifting section which causes the conveyor travel to rise and then to drop back to the main rail. .The height of fall may be as desired and may be interrupted by placing in the path of fall a stop member along Which the carriage will travel for a desired distance before Vdropping to the main track level. A galvanizing operation, utilizing conveyor apparatus, as disclosed herein produces an improved coating during the period ofimmersion in the kettle, and improved recovery of surplus zinc following removal of the Work from the kettle.

Other features and advantages of the invention will be apparent from the following detailed description of a presently preferred embodiment read in connection with the accompanying drawing in which:

Fig. l is a side elevation of a conveyor having lifting sections applied thereto according to the present invennited States Patent fice tions; said conveyor is shown in association with a galvanizing kettle displayed in section;

Fig. 2 is a side elevation of an installation of a lifting section showing an interrupter section arranged to cause the carriage to return to the main track in two short drops; and

Fig. 3 is an elevation taken in section on lines 3 3 of Fig. 2. v

In Fig. 1, ware such as domestic water heater tanks T are being conveyed into, through-and out of a galvanizing kettle K by a monorail conveyor C, suitably supported from an overhead structure (not shown) by the hanger rods H.

The main run of the conveyor is relatively conventional; that is to say, it comprises a monorail of inverted T-section, thus providing trackway portions 1, separated by a vertical web 2. The work carriage comprises the U-shaped yoke 3, having aligned shafts 4 on which are mounted the Wheels 5. It will be noted from the Fig. 3 that the transverse width of the yoke is substantially greater than that of the rail and that a multiplicity of carriages are associated seriatim by the connecting chains 6. Said chains are suitably linked to the outermost edges of the carriage so as to be beyond the side edges of the rail. The chain is, of course, drawn by suitable power (not shown) whereby the entire series of carriages is propelled along the rail at a controlled rate.

ln a continuous galvanizing system, the articles pass through several stages of pickling, washing, drying, uxing, etc., before they reach the galvanizing kettle. it

will be assumed, therefore, that all of these operationsl have been performed on the tanks which are approaching the left-hand end of the galvanizing kettle of Fig. 1. The conveyor approaches the kettle at a suitable clearance height, then dips for a gradual immersion of the tank. After traversing the kettlefor a period calculated properly to galvanize the tanks, the conveyor withdraws the work and conveys it to a further operational station.

As previously noted, it is advantageous to bump or jar the work While it is in the kettle and after it has emerged therefrom. Pursuant to the present invention, I provide lifter sections which may be applied (preferably by bolts 'or other removable fastenings) at any desired point along the conveyor track. As shown in Figs. 2 and 3, a lifter section 8 comprises a fabricated structure including spaced webs 9 arranged to straddle the track web 2 in contact therewith, ramp portions 10 supported by the webs and rising from the main trackways 1 to a dwell portion 11 at a desired height above the main trackway, and a web guard plate 12. Which occupies the vertical plane of the web2 to form an effective area enlargement thereof. It is obvious that the respective webs form a guide for the wheels 5, and therefore the web 12 extends forwardly of the ramp 10 and well beyond the rear edge of the dwell 11.

The extent of immersion of the Work is, of course, determined in large measure by the size and other vcharacteristics thereof, and hence the length of the horizontal run of the conveyor over the bath will be determined by local conditions. By providing one or more lifter sections, 'the Work may be bumped during its travel through the kettle. Under circumstances in which a single abrupt drop may be undesirable, the' fall may be interrupted by afxing short interrupter sections 14 to the opposite sides of Web 2, as shown in Figs. 2 and 3. Said sections may be of any desired length but preferably should commence at least one Wheel diameter uptravel of the end of the guide web 12.

After the work has been withdrawn from the kettle, the still-molten zinc begins to run down the surface of the work and to drop into the kettle. 'I'he freezing of the zinc depends somewhat on the heat capacity of the work and the speed with which it is withdrawn from the kettle. The beads or tears gathering at the bottom edge of the Work quickly become so viscousthat they do not drop freely into the kettle. It has been the practice to have a kettle attendant strike the work with a wooden pole to shake the droplets loose, but this has been a haphazard manual operation. By providing a lifter section on the horizontal run ot' conveyor track so as to bump the work as soon as is practicable after the work has been withdrawn from the zinc, the jarring [ree of zinc droplets becomes a controllable part of the galvanizing process and the recovery of surplus zinc is facilitated.

It should be understood that the height of the lifter sections above the main trackway surfaces 1 may he selected for the particular job conditions, although it is contemplated that the rise will be at least of the order of one wheel diameter. For rises greater than the depth of the web Z of the monorail, it is expedient to weld or otherwisc secure to the upper edge of the web 2 at the bases of the inclines of the monorail, guard plates 15 which ovcrlie the respective carriage wheels 5 to prevent them from being raised from the track as an adjacent tank is ascending a lifter section.

It will be understood that although the invention has been described with particular reference to hot-dip galvanizing, the lifter sections also have adaptability to continuous plating operations. For example: at intervals along the travel of the work through the plating bath, the work may be jarred or shaken to cause the separation therefrom of gas bubbles which may have accumulated thereon.

Also, it is advantageous to cause the work to travel at a predetermined time at one level within the electroplating solution, then shift to another level in which the metal ions are less depleted. Following a period of travel at the second level, the work may pass to a third level` or return to the original level. The multi-level travel is readily accomplished pursuant to the present invention by making the length of travel along the dwell portions 1l and the interrupter portions 14 as desired.

While l have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made; and l therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

I claim:

1. In a conveyor' system for conveying articles into, through, and out of a liquid treatment bath, the combination comprising a main conveyor rail disposed above said bath, said rail having a substantially horizontal trackway portion from a side edge of which a coextensive web portion rises substantially vertically, a wheeled carriage riding on said trackway, said carriage having a yoke disposed beneath said trackway for the support of an article to be treated, means for propelling said carriage along said trackway, and a lifter section arranged to be xed to said rail to raise said carriage temporarily above the level of said rail, said section including a ramp engaging said trackway portion for interception of said carriagevwheels to divert said carriage from said trackway portion and rising to a dwell portion disposed above said traekway portion in overlying relation therewith, an upstanding guard plate extending upwardly from a side edge of said dwell portion in the plane of said web portion, said lifter section terminating abruptly above said trackway portion to permit said carriage to drop sharply toward said trackway portion after traversing said dwell portion, and means for removably attaching said lifter section rigidly to said conveyor rail.

2. In a conveyor system of conveying articles into, through, and out of a liquid treatment bath, the combination comprising a main conveyor rail disposed above said bath, said rail being of inverted T formation and having a substantially horizontal trackway portion from the centerline of which a coextensive web portion rises substantially vertically, a wheeled carriage riding on said trackway, said carriage having a yoke disposed beneath said trackway for the support of an article to be treated, means for propelling said carriage along said trackway, and a lifter section arranged to be applied to said rail to raise said carriage temporarily above the level of said rail, said section including a ramp engaging said trackway portion on each side of said web for interception of said carriage wheels to divert said carriage from said trackway portion and rising to a dwell portion disposed above said trackway portion in overlying relation therewith, an upstanding guard plate extending upwardly from said dwell portion in the plane of said web portion, said lifter section terminating abruptly above said trackway portion to permit said carriage to drop sharply toward said trackway portion after traversing said dwell portion, and means for removably attaching said lifter section rigidly to the web of said conveyor rail.

3. A conveyor system as in claim 2, in which said guard plate extends in the down-travel direction at least one carriage-wheel diameter beyond the terminal edge of said dwell portion.

4. ln a conveyor system for conveying articles into, through, and out of an elongated liquid treatment bath, the combination comprising a main conveyor rail disposed above said bath, a carriage arranged to be drawn along said rail by means disposed outwardly of the side edges of said rail, means for suspending articles from said carriage for treatment in said bath, a lifting section arranged to be secured to said rail and arranged to raise said carriage temporarily above the level of said rail, said section having a ramp portion to divert said carriage upwardly from said rail and rising to a dwell portion extending in the direction of said rail in spaced relation therewith, said lifting section terminating abruptly to permit said carriage to drop toward said rail, and an interrupter section disposed intermediate said dwell portion and said rail to interrupt said drop and interpose a second dwell portion along which said carriage may travel in the direction of said rail, said interrupter section terminating abruptly to permit said carriage nally to drop to said rail for continued travel therealong.

References Cited in the file of this patent UNITED STATES PATENTS 

